Atomic qubit manipulations with an electro-optic modulator

We report new techniques for driving high-fidelity stimulated Raman transitions in trapped-ion qubits. An electro-optic modulator induces sidebands on an optical source, and interference between the sidebands allows coherent Rabi transitions to be efficiently driven between hyperfine ground states separated by 14.53 GHz in a single trapped 111Cd+ ion.     

Off-axis effects on the multipulse structure of sperm whale usual clicks with implications for sound production

Sperm whales (Physeter macrocephalus) produce multipulsed clicks with their hypertrophied nasal complex. The currently accepted view of the sound generation process is based on the click structure measured directly in front of, or behind, the whale where regular interpulse intervals (IPIs) are found between successive pulses in the click. Most sperm whales, however, are recorded with the whale in an unknown orientation with respect to the hydrophone where the multipulse structure and the IPI do not conform to a regular pulse pattern. By combining far-field recordings of usual clicks with acoustic and orientation information measured by a tag on the clicking whale, we analyzed clicks from known aspects to the whale. We show that a geometric model based on the bent horn theory for sound production can explain the varying off-axis multipulse structure. Some of the sound energy that is reflected off the frontal sac radiates directly into the water creating an intermediate pulse p1/2 seen in off-axis recordings. The powerful p1 sonar pulse exits the front of the junk as predicted by the bent-horn model, showing that the junk of the sperm whale nasal complex is both anatomically and functionally homologous to the melon of smaller toothed whales.     

Exact nondipole Kramers-Henneberger form of the light-atom hamiltonian: an application to atomic stabilization and photoelectron energy spectra

The exact nondipole minimal-coupling Hamiltonian for an atom interacting with an explicitly time- and space-dependent laser field is transformed into the rest frame of a classical free electron in the laser field, i.e., into the Kramers-Henneberger frame. The new form of the Hamiltonian is used to study nondipole effects in the high-intensity, high-frequency regime. Fully three-dimensional nondipole ab initio wave packet calculations show that the ionization probability may decrease for increasing field strength. We identify a unique signature for the onset of this dynamical stabilization effect in the photoelectron spectrum.     

Spatial distribution of cold antihydrogen formation

Antihydrogen is formed when antiprotons are mixed with cold positrons in a nested Penning trap. We present experimental evidence, obtained using our antihydrogen annihilation detector, that the spatial distribution of the emerging antihydrogen atoms is independent of the positron temperature and axially enhanced. This indicates that antihydrogen is formed before the antiprotons are in thermal equilibrium with the positron plasma. This result has important implications for the trapping and spectroscopy of antihydrogen.     

Intermediate mass strangelets are positively charged

For a limited range of parameters, stable strange quark matter may be negatively charged in bulk due to one gluon exchange interactions. However, the reduction in strange quark occupation in the surface layer, which is responsible for surface tension, more than compensates this for intermediate mass strangelets, which therefore always have positive quark charge (e.g., for a baryon number between 10(2) and 10(18) assuming alpha(S) = 0.9). While details are sensitive to the choice of renormalization, the general conclusion is not. This rules out a scenario where negatively charged strangelets produced in ultrarelativistic heavy ion colliders might grow indefinitely with potentially disastrous consequences.     

Methods for solving combined two level location-routing problems of realistic dimensions

Very few distribution studies have dealt with combined location-routing problems, the problems of locating depots from which customers are served by tours rather than individual trips.This paper gives a survey of methods solving combined location-routing problems. Some methods are analyzed and three new heuristic methods are developed, implemented and compared.A newspaper delivery system consisting of 4500 customers is solved. The results seem to indicate that an alternate location-allocation-savings procedure and a saving-drop procedure are promising.     

The entropy difference between the Lennard-Jones crystalline and glassy states

Entropy changes of isochoric Lennard-Jones fluid-crystal and fluid-glass transitions, calculated by molecular dynamics and integration of $\text{d}\text{S =}\text{d}\text{Q}\text{T}$, are approximately equal. The entropy difference between crystal and glass, at the same density and temperature, is thus negligibly small.     

Theory of long induction periods

Current theories relating induction periods in crystallization to either stationary nucleation rate or relaxation time of embryo distribution are of limited validity. The Zeldovich-Frenkel theory overestimates the growth rate of postcritical embryos with high surface energy. Growth of embryos by surface nucleation accounts well for some cases of long induction periods, structural anomalies of nuclei accounts for others. Finally, slow chemical reactions in solution or in the adlayer may retard crystallization.